Botulinum toxin type A for controlling bruxism assessed with computerized occlusal analysis: A pilot study.

Objective: To assess botulinum toxin-A (BTX-A) on mandibular movements and bite force (BF%) in bruxism.Methods: Ten bruxers were divided into 2 groups based on BF% imbalance (G1: >10%, G2: <10%). BTX-A 140U was total injected into the masseter and temporalis muscles. A T-Scan® recorded BF%, occlusion time (OT), right, left, and protrusive disclusion time (DT) before administering BTX-A, as well as 15, 45, 90, and 120 days after injection.Results: The Friedman and Wilcoxon tests found significant differences in BF% in G1 subjects at 15 days (p = 0.028 s), OT at 90 (p = 0.043 s), and 120 (p = 0.027 s) days, DTR at 90 (p = 0.046 s) and 120 (p = 0.028 s) days, DTL at 15 (p = 0.043 s) and 90 (p = 0.027 s) days, and DTP 45-90 days (p = 0.043 s).Conclusion: BTX-A induced BF% starting at 15 days post-injection and influenced lateralities later.

A Multi-Center Disclusion Time Reduction (DTR) Randomized Controlled Occlusal Adjustment Study Using Occlusal Force and Timing Sensors Synchronized with Muscle Physiology Sensors.

Objective-To perform a Randomized Controlled Trial (RCT) Disclusion Time Reduction (DTR) study at five Dental Colleges, using intraoral sensors and muscular electrodes. Methods and Materials-One hundred students were randomly assigned to a treatment group to receive the ICAGD coronoplasty, or a control group that received tooth polishing. All subjects answered symptom questionnaires: Beck Depression Inventory-II, Functional Restrictions, and Chronic Pain Symptom and Frequency. Subjects self-reported after ICAGD or placebo at 1 week, 1 month, 3 months, and 6 months. The Student's t-Test analyzed the measured data. The Mann-Whitney U Test analyzed the subjective data (Alpha = 0.05). Results-The Disclusion Times, BDI-II scores, and Symptom Scales were similar between groups prior to treatment (p > 0.05). At 1 week, all three measures reduced in the treatment group, continuing to decline over 6 months (p < 0.05), but not for the controls (p > 0.05). Symptom Frequency, Functional Restrictions, and Pain Frequencies were higher in the treated group (p < 0.05), but declined after ICAGD compared to the control group (p < 0.05). Conclusions-ICAGD reduced Pain, Functional Restrictions, Symptom Frequency, and Emotional Depression within 1 week, which continued for 6 months. The tooth polishing did not initiate a placebo response.

Comparison of excursive occlusal force parameters in post-orthodontic and non-orthodontic subjects using T-Scan® III.

OBJECTIVE: Published studies indicate that orthodontically treated patients demonstrate increased posterior occlusal friction contributing to temporomandibular disorder (TMD) symptoms. This study investigated measured excursive movement occlusal contact parameters and their association with TMD symptoms between non- and post-orthodontic subjects. METHODS: Twenty-five post-orthodontic and 25 non-orthodontic subjects underwent T-Scan® computerized occlusal analysis to determine their disclusion time (DT), the excursive frictional contacts, and occlusal scheme. Each subject answered a TMD questionnaire to determine the presence or absence of TMD symptoms. Statistical analysis compared the within group and between group differences (p < 0.05). RESULTS: Statistically significant differences were observed in the disclusion time: DT = 2.69 s in the post-orthodontic and 1.36 s in the non-orthodontic group. In the non-orthodontic group, 72.7% working and 27.3% non-working side contacts were seen, while in the post-orthodontic group, (near equal) 54.7% working and 45.3% non-working side contacts were seen. Presence of canine guidance was seen in 60% of the non-orthodontic group and 24% in the post-orthodontic group. Seventy-two percent of the post orthodontics subjects presented with one or more TMD symptoms. CONCLUSION: Significantly longer disclusion time, higher posterior frictional contacts, and more TMD symptoms were observed in the post-orthodontic group, suggesting that orthodontic treatment increases posterior tooth friction. Computerized occlusal analysis is an objective diagnostic tool determining the quality of excursive movements following orthodontic treatment.

Disclusion time reduction therapy in treating occluso-muscular pains.

Disclusion time reduction (DTR) is an objective treatment protocol using T-Scan III (digital analysis of occlusion) and electromyography for treating occlusally activated orofacial pains. Chronic occluso-muscle disorder is a myogenous subset of temporomandibular disorder symptoms. These muscular symptoms are induced within hyperactive masticatory muscles due to prolonged disclusion time, occlusal interferences, and occlusal surface friction that occur during mandibular excursive movements. This case report describes a patient treated by DTR therapy, whereby measured pretreatment prolonged disclusion time was reduced to short disclusion time using the immediate complete anterior guidance development enameloplasty, guided by T-Scan occlusal contact time and force analysis synchronized with electromyographic recordings of four masticatory muscles.

Average chewing pattern improvements following Disclusion Time reduction.

OBJECTIVES: Studies involving electrognathographic (EGN) recordings of chewing improvements obtained following occlusal adjustment therapy are rare, as most studies lack 'chewing' within the research. The objectives of this study were to determine if reducing long Disclusion Time to short Disclusion Time with the immediate complete anterior guidance development (ICAGD) coronoplasty in symptomatic subjects altered their average chewing pattern (ACP) and their muscle function. METHODS: Twenty-nine muscularly symptomatic subjects underwent simultaneous EMG and EGN recordings of right and left gum chewing, before and after the ICAGD coronoplasty. Statistical differences in the mean Disclusion Time, the mean muscle contraction cycle, and the mean ACP resultant from ICAGD underwent the Student's paired t-test (α = 0.05). RESULTS: Disclusion Time reductions from ICAGD were significant (2.11-0.45 s. p = 0.0000). Post-ICAGD muscle changes were significant in the mean area (p = 0.000001), the peak amplitude (p = 0.00005), the time to peak contraction (p < 0.000004), the time to 50% peak contraction (p < 0.00001), and in the decreased number of silent periods per side (right p < 0.0000002; left p < 0.0000006). Post-ICAGD ACP changes were also significant; the terminal chewing position became closer to centric occlusion (p < 0.002), the maximum and average chewing velocities increased (p < 0.002; p < 0.00005), the opening and closing times, the cycle time, and the occlusal contact time all decreased (p < 0.004-0.0001). CONCLUSION: The average chewing pattern (ACP) shape, speed, consistency, muscular coordination, and vertical opening improvements can be significantly improved in muscularly dysfunctional TMD patients within one week's time of undergoing the ICAGD enameloplasty. Computer-measured and guided occlusal adjustments quickly and physiologically improved chewing, without requiring the patients to wear pre- or post-treatment appliances.

Treatment of frictional dental hypersensitivity (FDH) with computer-guided occlusal adjustments.

OBJECTIVE: To verify the efficacy of treating dentin/dental hypersensitivity (DH) to Cold Ice Water Swish testing before and after subjects undergo the Immediate Complete Anterior Guidance Development (ICAGD) computer-guided occlusal adjustment. METHODS: One hundred chronically dysfunctional patients with known cold sensitivity swished ice water intraorally to elicit a DH response scored on a Visual Analog Scale (VAS). The subjects then underwent the ICAGD coronoplasty, which was followed by a second ice water swish scored with a second VAS. The pre to post ICAGD Disclusion Time values and VAS scores were statistically evaluated by the Wilcoxon Signed Rank for Paired Difference test. The subjects were divided into subgroups with DH sensitivities <4 and ≥4, and analyzed. Limitations were as follows: abfractions were not quantified, dysfunctional symptom resolution was not determined, each subject was their own control, one clinician administered all ice water tests, and protrusive excursions were not included. RESULTS: Disclusion Time reductions from ICAGD were significant (2.11-0.55 s. p = 0.0000). The DH score changes showed highly significant decreases from pre to post ICAGD (p < 0.0001). CONCLUSIONS: A partial etiology for cold tooth sensitivity exists, resultant from prolonged occlusal surface excursive movement frictional contacts. This cold sensitivity can be lessened with measured, computer-guided occlusal adjustments.

Comparison of closure occlusal force parameters in post-orthodontic and non-orthodontic subjects using T-Scan® III DMD occlusal analysis.

OBJECTIVE: Balanced occlusal force distribution is a critical factor for restorative, prosthetic or orthodontic treatment. It has been postulated that orthodontic treatment may lead to occlusal discrepancies in the arch due to changing the occlusal relationships. This study was conducted to compare the occlusal force parameters between natural dentition patients and a post-orthodontic treatment group. METHOD AND MATERIALS: Fifty Thai subjects were divided into non-orthodontic and post-orthodontic groups comprised of 25 subjects each (mean age 24.8 years). The T-Scan® III computerized occlusal analysis system was used to record a multi-bite closure for each subject. The initial occlusal contact location, the bilateral percentage force distribution, the percentage force in the anterior and posterior quadrants, and the individual tooth force percentages were calculated for both groups. The Student's Paired t-Test compared the in-group differences, while a one-way ANOVA analyzed the differences between the two groups. RESULTS: The initial tooth contacts in both groups were found on the second molars and central incisors. Maximum force was most frequently observed on the left second molar tooth (15.9% non-orthodontic; 25.4% post-orthodontic). The bilateral right-to-left side force distribution (51.36% right-48.96% left) was not statistically different for all subjects, nor was it statistically different between the non-orthodontic (48.67% right-51.36% left) and the post-orthodontic groups (48.96% right-51.05% left). Statistically significant differences were found between the quadrants in both the groups (22.46% anterior-77.57% posterior in non-orthodontic subjects; 10.58% anterior-89.42% posterior in post-orthodontic subjects) (p < 0.01). CONCLUSION: A significant occlusal force discrepancy was found in the post-orthodontic subjects, with higher force percentages observed posteriorly and much less percentage force anteriorly, when compared to the natural dentition subjects. T-Scan® III digital occlusal analysis may be recommended for orthodontic case finishing, to make visible to the clinician the severity of the orthodontically created occlusal force imbalance, such that it can be minimized during orthodontic case finishing.

Clinician accuracy when subjectively interpreting articulating paper markings.

AIMS: The aim of this study was to determine whether Subjective Interpretation of paper markings is a reliable method for identifying the relative occlusal force content of tooth contacts. METHODOLOGY: 295 clinicians selected the "Most Forceful" and "Least Forceful" occlusal contacts in six occlusal-view photographs of articulating paper marks that were later compared against computerized occlusal analysis relative occlusal force measurements of the same tooth contacts. Means and standard deviations were calculated by years in clinical practice and by number of occlusion courses taken. A Chi-square analysis was also performed. RESULTS: The mean correct for 295 participant dentists was 1.53 (+/- 1.234). There were no significant differences found for years in practice (P>0.16) or number of occlusion courses taken (P>0.75). The Chi-square analysis showed a sensitivity of 12.6%, a specificity of 12.4%, a positive predictive value of 12.58%, and a negative predictive value of 12.42%. Chance was calculated at 12.5% correct. CONCLUSIONS: Subjective Interpretation is an ineffective clinical method for determining the relative occlusal force content of tooth contacts. The reported low scores obtained from a large group of participant dentists suggest clinicians are unable to reliably differentiate high and low occlusal force from looking at articulating paper marks. This longstanding method of visually observing articulating paper marks for occlusal contact force content should be replaced with a measurement-based, objective method.

Force Finishing and Centering to Balance a Removable Complete Denture Prosthesis Using the T-Scan III Computerized Occlusal Analysis System.

Obtaining bilateral balance of removable complete denture prostheses is the occlusal goal of the restorative dentist or prosthodontist. Despite our best clinical efforts, and the using of advanced mechanical devices like semi-adjustable articulators and face bow transfer mounting of dental casts, it is a struggle to provide accurate occlusal force balance. Some of the advocated reasons for the clinical difficulty of obtaining reliable occlusal balance are that stone casts lack soft tissue resiliency, and articulators only approximate human occlusal functional movements. However, modern technology offers clinicians a digital answer to this clinical force balance problem. It is known as computerized occlusal analysis. The T-Scan III system can be employed with complete removable denture prostheses to perform computer-guided occlusal force-finishing corrective adjustments that measurably improve the installed prosthetic occlusal balance.

Masseter and temporalis excursive hyperactivity decreased by measured anterior guidance development.

The purpose of this study was to determine if a statistically significant reduction in muscle activity (p<0.05) occurs when prolonged disclusion time (>0.4 sec/excursion) is shortened to <0.4 sec/excursion with the Immediate Complete Anterior Guidance Development (ICAGD) enameloplasty. Forty-five symptomatic, fully informed subjects (29 female, 16 male) had their right and left disclusion times recorded with T-Scan III, while simultaneously, the bilateral masseter and anterior temporalis muscle activity was recorded electromyographically with BioEMG III (n=180 muscles). This recording was done twice, once pretreatment and again posttreatment (same day) after undergoing the ICAGD enameloplasty on the same day without changing electrodes. The Student's paired t-test was utilized to detect any significant change in the muscle activity levels between the pre- and posttreatment lateral excursive muscle contractions. Highly significant reductions were found in all four muscles' activities after shortening the pretreatment prolonged disclusion time to less than 0.4 seconds (p<0.0014); after Bonferroni correction (p<0.006). When properly performed, such that the posttreatment disclusion time is <0.4 sec/excursion, the ICAGD enameloplasty predictably reduces excursive muscle activity levels in the bilateral anterior temporalis and masseter muscles. Excursive muscle hyperactivity can be a source of lactic acid accumulation, muscular ischemia, and chronic myalgic temporomandibular joint dysfunction (TMD) symptoms. The ICAGD enameloplasty significantly reduces excursive muscle contractions after completion of the first ICAGD treatment session.

Reducing chronic masseter and temporalis muscular hyperactivity with computer-guided occlusal adjustments.

Muscle hyperactivity is a potential source of symptomatology in patients with temporomandibular disorders. Various occlusal adjustment procedures have been advocated to reduce hyperactivity. A new, measurement-driven, occlusal adjustment procedure, known as immediate complete anterior guidance development (ICAGD), has been shown through nonsimultaneous electromyography to lessen masticatory muscle hyperactivity effectively by reducing posterior disclusion time to <0.4 sec in all mandibular excursions. This reduction, in turn, lessens the volume of periodontal ligament compressions that create additive and excessive functional muscle contractions via a feedback mechanism involving the trigeminal nerve. This case report describes the treatment of chronic muscular hyperactivity with a computer-guided ICAGD enameloplasty and simultaneously recorded electromyography. Follow-up visits showed that after reduction, the pretreatment levels of excursive muscular hyperactivity were lessened and lasting. This result is caused by the shorten ed posterior disclusio time resulting in an equally reduced time to muscle shutdown.

Articulating paper mark misconceptions and computerized occlusal analysis technology.

Articulating paper mark size is now understood to be non-descriptive of occlusal loads; in fact, many different sized marks can represent the same load, and equal sized marks do not represent similar loads. With a reported reliability between mark size and applied occlusal load of only 21%, choosing the paper marks to occlusally adjust, based upon their relative size and operator-subjective assessment of those various sizes, is tantamount to clinical guessing. Computerized occlusal analysis completely removes the operator subjectivity from the clinical decision-making process when attempting to isolate problem occlusal contacts. When an operator properly uses this technology, mark size, mark color-depth, donut-shaped halo contacts, as well as other color and mark appearance characteristics, are ignored as force indicators and used only as contact locators. Operator-subjective paper mark misperceptions are replaced with accurate knowledge of the true and measured contact order, contact applied load, contact quality, and proper contact isolation where problematic. This results in better overall force application to any installed implant prostheses during occlusal function, thereby enhancing its chance for an undamaged clinical service lifespan.

Improving darkened anterior peri-implant tissue color with zirconia custom implant abutments.

Tissue discoloration in the cervical third of anterior implant restorations may result from implant abutment material show-through. As an alternative to metal abutments that may compromise the appearance of tissue color in the esthetic zone, zirconia abutments can be used. When zirconia abutments are combined with all-ceramic crowns, the appearance of the peri-implant tissue can be noticeably improved. This article describes two cases where a zirconia abutment replaced an existing metal abutment in a single anterior implant restoration.

A comparison of fabrication precision and mechanical reliability of 2 zirconia implant abutments.

PURPOSE: Studies have described the reliability of zirconia as an implant abutment material. The purpose of this in vitro study was to compare the precision and fracture strength of 2 different zirconia abutments angled at 30 degrees and loaded to failure in a standardized testing device. MATERIALS AND METHODS: Twenty-nine Atlantis abutments in zirconia (AAZ) and 29 Nobel Biocare Procera AllZirkon abutments of comparable interface were measured for key interface feature statistical differences (analysis of variance; alpha = 95%). Each specimen was fixed to a regular-platform Brånemark System implant and mounted in an Instron machine. Increasing incremental loads were applied until failure. A 2-tailed t test for independent specimens and unequal variances was employed (alpha = 95%). The Weibull method determined the probability of failure of each abutment sample (alpha = 95%). Fractography by scanning electron microscopy determined the flaws at the fracture origins. RESULTS: Metrology inspection indicated that the AAZ showed no measurable dimensional differences of 4 key interface features. The mean failure load of the AAZ (831 N) was greater than the AllZirkon (740 N; P < .00006). The Weibull distribution showed that the AAZ would be more likely to survive intraoral occlusal loads (P < .0005). CONCLUSIONS: Both types of zirconia abutments demonstrated failure loads that exceed maximum human bite force. In vitro, the AAZ outperformed the AllZirkon in survivability. The clinical use of zirconia abutments is indicated when esthetics may be of concern.

Determining a relationship between applied occlusal load and articulating paper mark area.

Articulating paper mark size has been widely accepted in the dental community to be descriptive of occlusal load. The objective of this study is to determine if any direct relationship exists between articulating paper mark area and applied occlusal load. A uniaxial testing machine repeatedly applied a compressive load, beginning at 25N and incrementally continuing up to 450N, to a pair of epoxy dental casts with articulating paper interposed. The resultant paper markings (n = 600) were photographed, and analyzed the mark area using a photographic image analysis and sketching program. A two-tailed Student's t-test for unequal variances compared the measured size of the mark area between twelve different teeth (p < 0.05). Graphical interpretation of the data indicated that the mark area increased non-linearly with increasing load. When the data was grouped to compare consistency of the mark area between teeth, a high variability of mark area was observed between different teeth at the same applied load. The Student's t-test found significant differences in the size of the mark area approximately 80% of the time. No direct relationship between paper mark area and applied load could be found, although the trend showed increasing mark area with elevating load. When selecting teeth to adjust, an operator should not assume the size of paper markings, accurately describing the markings' occlusal contact force content.

The effect of disclusion time reduction on maximal clench muscle activity levels.

Simultaneous recording of excursive function and muscle activity on 62 MPDS patients demonstrated that reducing prolonged disclusion time (1.4 seconds per excursion) to short disclusion time (0.41 seconds per excursion) created a therapeutic effect such that within one month's time following treatment, there was an observed increase in the maximal clenching capacity of the masseter and temporalis muscles. This clinical treatment effect appears to be the result of decreased ischemia in these same muscles resultant from minimizing the time posterior teeth compress their periodontal ligament mechanoreceptors as these teeth are engaged and disengaged during excursive function.

A force reproduction analysis of two recording sensors of a computerized occlusal analysis system.

The purpose of this study was to measure the performance of a new design of occlusal sensor, the high definition (HD) sensor, and directly compare this sensor to the previous design. This new HD sensor design has increased active recording area by 33%, and decreased inactive recording area by 50% as compared to the previous design (G3). This was accomplished by determining the force reproduction variability for repeated occlusal closures on the same sensor for a sampling of sensors from both designs. Thirty (30) G3 and 30 HD sensors were consistently positioned and loaded 24 times between articulated epoxy casts by a Pneumatic Occlusal Force Simulator. Their force reproduction consistency was measured as an electronic voltage drop across six occlusal contacts that were consistently located on all sensors. The force variability of the two sensor designs was determined by comparing the consistency of the voltage drops across the six occlusal contacts. An analysis of variance was employed to determine the variability of force reproduction over multiple closures across six occlusal contact regions. For five of the six contacts, the G3 sensor mean variances, were significantly larger (p < 0.05) than those of the HD sensor. The within sensor variability of the HD sensor was significantly less than that of the G3 sensor. Within the limitations of this study, the HD sensor exhibited less variable force reproduction than the G3 sensor for at least 20 in-laboratory loading cycles.

Combining technologies: a computerized occlusal analysis system synchronized with a computerized electromyography system.

Current advances in computer technologies have afforded dentists precision ways to examine occlusal contacts and muscle function. Recently, two separate computer technologies have been synchronized together, so that an operator can record their separate diagnostic data simultaneously. The two systems are: the T Scan II Occlusal Analysis System and the Biopak Electromyography Recording System. The simultaneous recording and playback capacity of these two computer systems allows the operator to analyze and correlate specific occlusal moments to specific electromyographic changes that result from these occlusal moments. This synchronization provides unparalleled evidence of the effect occlusal contact arrangement has on muscle function. Therefore, the occlusal condition of an inserted dental prosthesis or the occlusal scheme of the natural teeth (before and after corrective occlusal adjustments) can be readily evaluated, documented, and quantified for both, quality of occlusal parameters and muscle activity and the responses to the quality of the occlusal condition. This article describes their synchronization and illustrates their use in performing precision occlusal adjustment procedures on two patients: one who demonstrates occlusal disharmony while exhibiting the signs and symptoms of chronic myofascial pain dysfunction syndrome, and the other who had extensive restorative work accomplished but exhibits occlusal discomfort post-operatively.